The present invention involves the ejection of ink drops by way of forming gas or vapor bubbles in a bubble forming liquid. This principle is generally described in U.S. Pat No. 3,747,120 (Stemme). Each pixel in the printed image is derived ink drops ejected from one or more ink nozzles. In recent years, inkjet printing has become increasing popular primarily due to its inexpensive and versatile nature. Many different aspects and techniques for inkjet printing are described in detail in the above cross referenced documents.
Distributing ink through micron-scale conduits to individual MEMS nozzles in an inkjet printhead is complicated by factors that do not arise in macro-scale flow. A meniscus can form at small apertures and, depending on the geometry of the aperture, the meniscus can ‘pin’ itself to the lip of the aperture quite strongly. This can be useful in printheads, such as bleed holes that vent trapped air bubbles but retain the ink, but it can also be problematic if stops ink flow to some chambers. This will most likely occur when initially priming the printhead with ink. If the ink meniscus pins at the ink inlet opening, the chambers supplied by that inlet will stay unprimed.